# Copyright 2020 The Flutter Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Helper functions for Flutter LUCI configs."""

def _merge_dicts(a, b):
    """Returns a new dictionary from the result of merging a and b.

    If matching values are both dicts or both lists, they will be merged (non-recursively).

    Args:
      a: first dict.
      b: second dict (takes priority).

    Returns:
      Merged dict.
    """
    new_dict = dict()
    a = dict(a)
    for k, av in a.items():
        new_dict[k] = av
    for k, bv in b.items():
        av = a.get(k)
        if type(av) == "dict" and type(bv) == "dict":
            new_dict[k] = dict(av)
            new_dict[k].update(bv)
        elif type(av) == "list" and type(bv) == "list":
            new_dict[k] = av + bv
        else:
            new_dict[k] = bv
    return new_dict

def _merge_lists(a, b):
    """Return the result of merging two lists.

    Args:
      a: first list.
      b: second list (takes priority).

    Returns:
      Merged list.
    """
    merged = []
    for item in b:
        merged.append(item)
    for item in a:
        if item not in merged:
            merged.append(item)
    return merged

helpers = struct(merge_dicts = _merge_dicts, merge_lists = _merge_lists)